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Homework Help: Is this mastering physics problem incorrect?

  1. Jul 25, 2015 #1
    1. The problem statement, all variables and given/known data
    This is the Diagram-The figure shows the circular wave fronts emitted by two wave sources.
    part B is the one with trouble it asks "Make a table with rows labeled P, Q, and R and columns labeled r1, r2, Δr, and C/D. Fill in the table for points P, Q, and R, giving the distances as multiples of λ and indicating, with a C or a D, whether the interference at that point is constructive or destructive."
    The given wave lengths to fill in the charts blank spaces are (1/2)λ,,,λ,,,(3/2)λ,,,2λ,,,(5/2)λ,,,(3)λ and then c for constructive and D for destructive for the last column.
    2. Relevant equations abs(r1-r2)=Δr and for C/D and Δr that is a natural number is C all decimal numbers are Destructive //sorry don't know how to put that into more mathematical format//
    3. The attempt at a solution

    the chart should look like- Unfortunately their is no 3.5 fraction 7/2 is missing^
    r1 r2 Δr D/C
    P 2λ 3.5λ 1.5λ D
    Q 3λ 2λ 1λ C
    R 2.5λ 3.5λ 1λ C
  2. jcsd
  3. Jul 25, 2015 #2


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    Hello and welcome to PF!

    To my eyes, the first wavefront surrounding source 1 is a full wavelength from source 1. But the first wavefront surrounding source 2 is not a full wavelength from source 2. Could it be that the two sources are not in phase?
  4. Jul 25, 2015 #3
    Yes your right so instead of 3.5 it would be 3 making it work thank you
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